Add Gist sharing support

[ci] Use aptitude's solver for 32 bit gcc toolchain install

`apt-get` solver cannot realize the constraints (and package
removals), which prevents install of the 32-bit gcc toolchain.

`aptitude`'s solver works for now, so we use it.

This kind of package conflicts do remain a big PITA.

`jscoq.js` is needed.

Signed-off-by: Elad Kinsbruner <kinsbruner@campus.technion.ac.il>

Added standard c_flags to jscoq_extern.

In scratchpad only.
Closes #326.

New in 8.17.

Instead of `.cjs`; enough with this nonsense.

[layout] Port to TS

[package manager] Port to TS

[editor] Port editor code to TS.

[build] Move frontend build to esbuild, always pack.

This is more modular and provides a workflow speedup in many cases.

We also add a couple of bugfixes (tsconfig.json missing from dune
deps, missing await in esbuild.mjs)

These are the current numbers on release:

```
 261K -- dist/wacoq_worker.js
 369K -- dist/frontend/index.css
 583K -- dist/frontend/index.js
```